Line pressure ?

[32vMonte]

This isn't 3800 related but FWD W-body related. Seemed like the best place to put a question about a FWD gm trans.

So I have a 4t80e. It has a TCI trans controller on it and you can adjust line pressure on each gear accordingly.

It gives you a graph of pressure vs. tps %

The way it is set up now from how I bought the car as the TPS % increases the line pressure goes down. That seems ass backwards to me. I want to know is there anyone that knows anything about this kind of stuff that can give me tips on how to tune this controller.

What should be my max pressure that I shouldn't exceed and what should be my lowest that I should not drop below?

I don't want to hurt the fresh trans it still feels fine but put about 800 spirited driving miles on it before I knew the line pressure was set up like this.

LMK what you guys think.

Click to read more...

 

[Turbocharged400sbc]

i would have to double check eric's manuals but if i recall the pressure control system on the 4t80e utilizes two pressure pumps, with the scavenge pumps, and may not be a bleed type. the other side of your question should be if the 4L80e has a different pressure control than the 4t80e, if it's inverted (ie bleed vs pressure) then yeah i would say that table might be correct.

i do know the the 4t80e and 4l80e have the inverted shift sol B activation from the 65e so i know they share that aspect of controls.

i'll try to remember next time i'm over at eric's

 

[32vMonte]

Well It shifts alot nicer now I just went out and messed with it. My line pressure was going almost to zero under WOT. It doesn't show in actual PSI? but it shows in duty cycle. The shift where very violent even at part throttle.

And from park to shift it felt like a neutral bomb. Now with the pressure bumped to about 60-70% duty cycle you can not even feel it go in gear. It also did not spin them in the 1st-2nd shift before it now chirps them and spins for about a half second.

But I can't seem to get it to shift fast enough into 2nd and the pcm cuts timing and the motor falls on its face. It's getting better but every time I adjust the WOT shift time it gets worse and sometimes not.

Also I keep lowering my shift rpm from 1st-2nd and it doesn't do much. It got alot better tho. I guess I will learn by trial and error. Thats not the best way but it's working so far.

 

[32vMonte]

You have a pm 400SBC

 

[Turbocharged400sbc]

it is a bleed type system, low PWM freq means max pressure (ie solenoid mostly closed), high pwm is low pressure (solenoid mostly open)

it's usually set to no/very low pressure at the low rpm/low load area of the table and ramps up from there

this is the table the riv currently has
Transmission -> Shift Pressure -> Shift Pressure 2nd Performance
File Location: C:\Documents and Settings\JamesII\Desktop\Flashdrive\WhippledRiv\2009 6 9 TRACK VE tune 2.bin

0 1
1 8
2 15
3 20
4 25
5 35
6 45
7 55
8 65
9 75
10 85
11 95
12 98
13 98
14 98
15 98
16 98
17 98
18 98
19 98
20 98
21 98
22 98
23 98
24 98
25 98
26 98
27 98
28 98
29 98
30 98
31 98
32 98

 

[Turbocharged400sbc]

BTW every time you adjust something you may need to let the controller relearn your driving habits, if i recall the TCI does have limited learning

 

[32vMonte]

I would just hit apply for anything but the line pressures and it is in effect. The line pressure changes on the fly. You are right about the line pressure. I made it on pressure across the graph and it seemed better than before.

The problem was the first gear line pressure was too high for idle and thats why it was rough putting it into drive.